A nerve conduction velocity (NCV) test is used to assess nerve damage and dysfunction. The procedure measures how quickly electrical signals move through your peripheral nerves.
Your peripheral nerves are located outside of your brain and along your spinal cord. These nerves help you control your muscles and experience the senses. Healthy nerves send electrical signals more quickly and with greater strength than damaged nerves.
The NVC test helps your doctor differentiate between an injury to the nerve fiber and an injury to the myelin sheath, the protective covering surrounding the nerve. It can also help your doctor tell the difference between a nerve disorder and a condition where a nerve injury has affected the muscles.
Making these distinctions is important for proper diagnosis and determining your course of treatment.
An NCV test can be used to diagnose a number of muscular and neuromuscular disorders, including Guillain-Barre syndrome (GBS/AIDP), compression Neuropathies (carpal tunnel syndrome, ulnar/radial Neuropathy, peroneal Neuropathy), hereditary Neuropathies, radiculopathy, different types of demyelinating & axonal neuropathies, sciatic nerve problems & peripheral nerve injury.
An electromyography (EMG) test is often performed alongside an NCV test. An EMG test records the electrical signals moving through your muscles. This helps detect the presence, location, and extent of any disease that may damage the nerves and muscles.
Your doctor will place two electrodes on your skin, one that stimulates the nerve and one that records the stimulation. They may use a jelly or some kind of paste to help the electrode stick to the skin.
The nerve will be stimulated by a mild and brief electrical shock from the stimulating electrode. One common test, for example, stimulates nerves in the finger and records the stimulus with an electrode near the wrist. The entire test may take 20 to 30 minutes. The sensation may be uncomfortable, but it typically isn’t painful.
One advantage of an NCV test is that it’s considered an objective measurement of the health of a nerve, compared to subjective reports of pain or poor functioning.
However, any result has to be examined along with other information. Your doctor will compare the results of your test against a standard, or norm, of conduction velocities. There’s no single standard. The results are affected by your age, what part of the body is tested, perhaps your gender, or even where you live.
A velocity outside of the norm suggests the nerve is damaged or diseased. However, it doesn’t indicate exactly what caused the damage.
Your diagnosis will depend on other information in your medical history and your physical symptoms.
Treatment varies according to your specific condition, for example, and which nerve is affected